tau

Ancient Greek Alphabet

← sigma		→ upsilon
Τ τ Ancient Greek: ταῦ
Wikipedia article on tau

A tau (sense 3) used as the symbol of the Hospital Brothers of Saint Anthony in the Antoniterkloster Höchst, a former monastery in Höchst, a quarter of Frankfurt am Main, Hesse, Germany.

When a circle’s radius is 1 unit, its circumference is twice the value of pi (2π) or tau (τ; sense 7) units.

An image of neurons. The taus or tau proteins (sense 8) are stained red.

From Middle English tau, taue, from Latin tau, from Ancient Greek ταῦ (taû) and Hebrew תָּו (tav).

Sense 6 (“mathematical constant equal to 2π”) was used by Joseph M. Lindenberg in 1991, and popularized by the American educator and entrepreneur Michael Hartl in a 2010 paper which explains that τ resembles π; and that τ is the Greek equivalent of t, the first letter of turn, and 2π corresponds to one turn of a circle with a radius of one unit.^[1]

Sense 8.1 (“short for tau lepton or tau particle”) was coined by the American physicist Martin Lewis Perl (1927–2014) after the first letter of Ancient Greek τρίτον (tríton, “third”), since the tau lepton or tauon was the third charged lepton discovered.^[2]

• (Received Pronunciation) IPA^(key): /taʊ/, /tɔː/
• (General American) IPA^(key): /taʊ/, /tɔ/

  • Audio (General American); /taʊ/:

    (file)

• Rhymes: -aʊ, -ɔː

tau (plural taus)

2. The letter Τ / τ in the Greek alphabet; being the nineteenth letter of the Classical and Modern Greek, and the twenty-first letter of the Old and Ancient Greek alphabets.
3. Alternative form of taw; the 22nd and last letter of many Semitic alphabets/abjads, including Phoenician, Aramaic, Hebrew, Syriac, and Arabic.
   • 1847, Richard Edmund Tyrwhitt, Sermons Chiefly Expository, volume I, Oxford: John Henry Parker; F and J Rivington, London, page 366:

     Hence it appears that the spits, or skewers, on which and to which the lamb was fixed and fastened in order to be roasted, assumed the form of a cross, not such a tau-cross as is engraved in Dr. Oliver’s Historical Landmarks of Freemasonry, vol. i. p. 80. having three arms only like the Greek letter tau; but a cross like the ancient Hebrew tau, with four arms, though not necessarily all of equal length.

   • 1851, D Rock, Hierurgia; or Transubstantiation, Invocation of Saints, Relics, and Purgatory, Besides Those Other Articles of Doctrine Set Forth in the Holy Sacrifice of the Mass, Expounded; , 2nd edition, London: C. Dolman, , page 350:

     In the Spanish translation of Sallust, by the Infant Don Gabriel in 1772, called the Infant Sallust, there is a curious dissertation by Father Perez Bayer on the resemblance between the ancient Hebrew and Phœnician alphabets, in which it is observed that the Hebrew Tau was written in pure Phœnician, […]

   • 2017, Piers Vaughan, Capitular Development Course, 2nd edition, Rose Circle Publications, →ISBN, page 135:

     The tau is both the 19^th letter of the Greek alphabet, and also the 22^nd letter of the Hebrew alphabet. In this context, the Hebrew tau or tav is more pertinent.

5. A Τ-shaped object or sign; a Saint Anthony's cross, sometimes regarded as a sacred symbol.
   • 1658, Thomas Browne, “The Garden of Cyrus. . Chapter I.”, in Hydriotaphia, Urne-buriall, Together with The Garden of Cyrus, , London: Hen Brome , →OCLC, page 96:

     Nor ſhall we take in the myſticall Tau, or the Croſſe of our bleſſed Saviour, which having in ſome deſcriptions an Empedon or croſſing foot-ſtay, made not one ſingle tranſverſion.

   1. (Christianity) A crosier with a Τ-shaped head.
6. The ankh symbol (☥).

   Synonym: crux ansata

7. (astronomy) Chiefly written τ: used to designate the nineteenth star (usually according to brightness) in a constellation.
8. (finance) A measurement of the sensitivity of the value of an option to changes in the implied volatility of the price of the underlying asset.

   Synonyms: kappa, vega

   Hypernym: Greeks (includes a list of coordinate terms)

10. (mathematics, neologism) Chiefly written τ: an irrational and transcendental constant representing the ratio of the circumference of a Euclidean circle to its radius, equal to twice the value of pi (2π; approximately 6.2831853071).
12. (neurology) Short for tau protein (“a protein abundant especially in the neurons of the human central nervous system that stabilizes microtubules, and when misfolded is associated with forms of dementia such as Alzheimer's and Parkinson's diseases”).
    • 1999, Matt Ridley, Genome: The Autobiography of a Species in 23 Chapters, London: Harper Perennial, published 2004, →ISBN, page 263:

      Quite what that job is remains obscure, but one theory is that it is to stabilise another protein called tau, which is supposed in turn to keep in shape the tubular ‘skeleton’ of a neuron.

13. (physics) Chiefly written τ.
    1. Short for tau lepton or tau particle (“an unstable elementary particle which is a type of lepton, having a mass almost twice that of a proton, a negative charge, and a spin of ½; it decays into hadrons (usually pions) or other leptons, and neutrinos; a tauon”).
    2. (historical) Short for tau meson, now known as a kaon.

• tau on Wikipedia.Wikipedia
• tau cross on Wikipedia.Wikipedia
• tau (particle) on Wikipedia.Wikipedia
• tau protein on Wikipedia.Wikipedia
• turn (angle) on Wikipedia.Wikipedia
• tau (disambiguation) on Wikipedia.Wikipedia

• AUT, UAT, UTA, Uta, aut-, uta

tau

1. to give

• Kateřina Naitoro, A Sketch Grammar of 'Are'are: The Sound System and Morpho-Syntax (2013)

• IPA^(key): (Central, Balearic, Valencia)
• Rhymes: -aw

tau f (plural taus)

1. Tau; the Greek letter Τ (lowercase τ)
2. tav; the Hebrew letter ת
3. (religion) a tau cross

• IPA^(key):

tau n (indeclinable)

1. tau (Greek letter)

• “tau”, in Kartotéka Novočeského lexikálního archivu (in Czech)
• tau in Akademický slovník cizích slov, 1995, at prirucka.ujc.cas.cz

From Middle Dutch tau, thau, from Ancient Greek ταῦ (taû). Doublet of taw, tav.

• Audio:

  (file)

tau n (plural taus, diminutive tautje n)

1. tau (Greek letter)

• tau (letter) on the Dutch Wikipedia.Wikipedia ^nl

Borrowed from Ancient Greek ταῦ (taû).

Finnish Wikipedia has an article on:

Tau

Wikipedia ^fi

• IPA^(key): /ˈtɑu̯/,
• Rhymes: -ɑu
• Hyphenation^(key): tau

tau

1. tau (Greek letter)
2. tauon, tau (elementary particle)

• “tau”, in Kielitoimiston sanakirja [Dictionary of Contemporary Finnish]‎ (in Finnish) (online dictionary, continuously updated), Kotimaisten kielten keskuksen verkkojulkaisuja 35, Helsinki: Kotimaisten kielten tutkimuskeskus (Institute for the Languages of Finland), 2004–, retrieved 2023-07-03

• -tua

• (in the plural) taus (1990 spelling reform)

• IPA^(key): /to/

• Audio (Paris):

  (file)

• Homophones: taus, taux, tôt

tau m (plural tau or taus)

1. tau (Greek letter)
2. (physics) tau, tauon

• tauique

• “tau”, in Trésor de la langue française informatisé , 2012.

• tua

• IPA^(key): /ˈtaw/
• Rhymes: -aw
• Hyphenation: tau

tau m (plural taus)

1. tau (name of the Greek letter Τ, τ)

• “tau”, in Dicionario da Real Academia Galega (in Galician), A Coruña: Royal Galician Academy, 2012–2024

• to (in some dialects)

Middle Low German tô.

tau

1. (in some dialects) to

• taum
• taun
• taur

tau

1. sun

Hungarian Wikipedia has an article on:

tau

Wikipedia ^hu

From Ancient Greek ταῦ (taû).

• IPA^(key):
• Hyphenation: tau
• Rhymes: -u

tau (plural tauk)

1. tau (Greek letter)

• IPA^(key): /tauʔ/

tau

1. ought, should

Borrowed from Danish tøj.

• IPA^(key): /tʰøyː/
• Rhymes: -øyː

tau n (genitive singular taus, no plural)

1. fabric
2. clothing

• IPA^(key): /ˈta.u/
• Rhymes: -au, -u
• Hyphenation: ta‧u

tau

1. nonstandard form of tahu (“to know”).

Learned borrowing from Ancient Greek ταῦ (taû).

tau

1. tau (the letter Τ / τ in the Greek alphabet; being the nineteenth letter of the Classical and Modern Greek, and the twenty-first letter of the Old and Ancient Greek alphabets)

Italian Wikipedia has an article on:

tau

Wikipedia ^it

• IPA^(key): /ˈtaw/
• Rhymes: -aw
• Hyphenation: tàu

tau m or f (invariable)

1. tau (Greek letter)

• -uta, tua

tau

1. Rōmaji transcription of たう

tau

1. person

   na tau na pa-hi dà-nggu

   the person that I cried with

• Marian Klamer (1998) A Grammar of Kambera, Berlin, New York: Mouton de Gruyter, →ISBN, page 328

• tauo (Spanish orthography, obsolete)
• tawu (Súlat Wáwâ)

From Proto-Philippine *tau, from Proto-Malayo-Polynesian *tau, from Proto-Austronesian *Cau.

• IPA^(key): /ˈtau/
• Hyphenation: ta‧u

táu

1. person; human; man
2. someone; people; human being
3. boyfriend; girlfriend; lover

• IPA^(key): /təˈu/
• Hyphenation: ta‧u

taú

1. feast; party; banquet

tau

1. three

tau

1. second-person singular dative of tu

• IPA^(key): /ˈtau/,
• Hyphenation: ta‧u

From Inherited from Proto-South Sulawesi *tau, from Proto-Malayo-Polynesian *tau, from Proto-Austronesian *Cau.

tau (Lontara spelling ᨈᨕᨘ)

1. people, person, man
2. slave, laborer, coolie

Inherited from Proto-Malayo-Polynesian *taqu, from Proto-Austronesian *Caqu (“to know how, be able to, be skilled at”).

tau (Lontara spelling ᨈᨕᨘ)

1. friendly, amicably, being familiar with someone.
2. tame, domesticated

tau (Lontara spelling ᨈᨕᨘ)

1. This term needs a translation to English. Please help out and add a translation, then remove the text {{rfdef}}.

• A. A. Cense (2024) Makassaars-Nederlands woordenboek‎, Brill, →DOI

• tahu
• تاهو

From Proto-Malayic *tahu(ʔ), from Proto-Malayo-Chamic, from Proto-Malayo-Sumbawan, from Proto-Malayo-Polynesian *taqu, from Proto-Austronesian *Caqu.

• (Kedah) IPA^(key): /tau/
• IPA^(key): /ta.u/
• Rhymes: -au, -u

tau

1. (informal) Alternative form of tahu (“to know”)

Borrowed from English tau, from Ancient Greek ταῦ (taû).

• IPA^(key): /tau/

tau (Jawi spelling تاو, plural tau-tau, informal 1st possessive tauku, 2nd possessive taumu, 3rd possessive taunya)

1. the Greek letter tau (Τ or τ)

• “tau” in Pusat Rujukan Persuratan Melayu | Malay Literary Reference Centre, Kuala Lumpur: Dewan Bahasa dan Pustaka, 2017.

From Proto-Polynesian *taqu (compare Hawaiian kau), from Proto-Oceanic, from Proto-Malayo-Polynesian *taqun (compare Malay tahun, Tagalog taón).

tau

1. year (time it takes for the Earth to complete one revolution of the Sun)
2. year (time it takes for any planetary body to make one revolution around another body)
3. year (a period between set dates that mark a year)
4. year (scheduled part of a calendar year spent in a specific activity)
5. year (Julian year)
6. year (level or grade at school or college)

From Proto-Polynesian *tau, from Proto-Oceanic, from Proto-Malayo-Polynesian *taʀuq (compare Malay taruh).

tau

1. to settle

From Proto-Polynesian *tau, from Proto-Oceanic, from Proto-Malayo-Polynesian *taqu, from Proto-Austronesian *Caqu (compare Malay tahu).

tau (used in the form mātau)

1. knowledge

tau (used in the form mātau)

1. (stative) to know

• “tau” in John C. Moorfield, Te Aka: Maori–English, English–Maori Dictionary and Index, 3rd edition, Longman/Pearson Education New Zealand, 2011, →ISBN.

From Proto-Malayic *tahu(ʔ), from Proto-Malayo-Chamic, from Proto-Malayo-Sumbawan, from Proto-Malayo-Polynesian *taqu, from Proto-Austronesian *Caqu.

tau

1. to know

From Proto-Polynesian *taqu, from Proto-Oceanic, from Proto-Malayo-Polynesian *taqun.

tau

1. year

From Proto-Polynesian *tau, from Proto-Oceanic, from Proto-Malayo-Polynesian *taʀuŋ.

tau

1. fight

• IPA^(key):

From Old Frisian twā.

tau (Föhr-Amrum, Sylt, Heligoland)

1. two

• twäär (Mooring)

From Proto-Germanic *þwahaną.

tau

1. (Föhr-Amrum) to wash

• taui (Sylt)
• tüünj (Mooring)

Norwegian Wikipedia has an article on:

tau

Wikipedia ^no

From Old Norse tog (rope).

tau n (definite singular tauet, indefinite plural tau, definite plural taua or tauene)

1. a rope
2. (physics) tau lepton
3. tau (Greek letter)

• (rope): rep, reip

• ståltau
• taubane
• tauverk

tau

1. imperative of taue

• “tau” in The Bokmål Dictionary.

Norwegian Nynorsk Wikipedia has an article on:

tau

Wikipedia ⁿⁿ

From earlier and Old Norse tog (“rope”), from Proto-Germanic *taugō.

• tog (superseded)

tau n (definite singular tauet, indefinite plural tau, definite plural taua)

1. a rope

• (rope): reip

• ståltau
• taubane
• tauverk

Norwegian Nynorsk Wikipedia has an article on:

Bokstaven tau

Wikipedia ⁿⁿ

Borrowed from Ancient Greek ταῦ (taû).

tau m (definite singular tauen, indefinite plural tauar, definite plural tauane)

1. tau: The letter Τ/τ in the Greek, Hebrew and ancient Semitic alphabets, being the nineteenth letter of the Classical and Modern Greek, the twenty-first letter of Old and Ancient Greek.
2. (physics) tau lepton

• “tau” in The Nynorsk Dictionary.

• Tau, tua

From Latin talis.

• IPA^(key): /taw/

• Audio:

  (file)

tau m (feminine singular tala, masculine plural taus, feminine plural talas)

1. (Gascony, Provençal, Limousin, Vivaro-alpine, Auvergne) such

• tal

Polish Wikipedia has an article on:

tau

Wikipedia ^pl

Learned borrowing from Ancient Greek ταῦ (taû), from Phoenician 𐤕 (t /⁠taw⁠/).

• IPA^(key): /ˈtaw/

• Audio:

  (file)

• Rhymes: -aw
• Syllabification: tau

tau n (indeclinable)

1. tau (Greek letter Τ, τ)

• tau in Polish dictionaries at PWN

• Homophone: tal (Brazil)
• Rhymes: -aw
• Hyphenation: tau

tau m (plural taus)

1. tau (name of the Greek letter Τ, τ)
2. (physics) tauon

tau class 9/10 (plural ditau)

1. lion

• → Phuthi: idawû

• IPA^(key): /ˈtau/

• Audio (Colombia):

  (file)

• Rhymes: -au
• Syllabification: tau

tau f (plural taus)

1. tau; the Greek letter Τ, τ
2. tauon (elementary particle)

   Synonym: tauón

• (Greek script letter names) letra; alfa, beta, gamma, delta, épsilon, dseda, eta, zeta, iota, kappa, lambda, mi, ni, xi, ómicron, pi, ro, sigma, tau, ípsilon, fi, ji, psi, omega ^{(Category: es:Greek letter names)}
• (leptons) leptón; electrón, muón, tau/tauón, neutrino electrónico, neutrino muónico, neutrino tauónico

• “tau”, in Diccionario de la lengua española [Dictionary of the Spanish Language] (in Spanish), online version 23.8, Royal Spanish Academy [Spanish: Real Academia Española], 2024 December 10

tau

1. some

• nau

• Yves Lemaître, Lexique du tahitien contemporain (Current Tahitian lexicon), 1995.
• “tau” in Dictionnaire en ligne Tahitien/Français (Online Tahitian–French Dictionary), by the Tahitian Academy.

From Proto-Malayo-Polynesian *tau.

• (Sinūgan Parianun) IPA^(key): /taʔu/
• Rhymes: -u
• Syllabification: ta‧u

tau (Sulat Sūg spelling تَؤُ)

1. person
2. human

• IPA^(key):

tau

1. to pull

• Rika Hayami-Allen (2001) A descriptive study of the language of Ternate, the northern Moluccas, Indonesia, University of Pittsburgh

From Proto-Malayo-Polynesian *taʀuq, compare Maori tau and Indonesian taruh.

tau

1. to put, to place

From Middle Chinese 斗 (MC tuwX).^[1][2]

tau ? sg (irregular plural towä or tom or taum)

1. a dry measure, roughly equivalent to ten quarts or 1.25 pecks

• IPA^(key):
• Hyphenation: ta‧u

From Proto-Polynesian *te-qa-u.

tau

1. (alienable, definite) thy, your

From Proto-Polynesian *taqu. Cognates include Hawaiian kau and Samoan tau.

tau

1. season
2. weather
3. climate

From Proto-Polynesian *tau. Cognates include Tongan tou and Samoan tau.

tau

1. (transitive) to pick

• tau is used to refer to flowers and fruits, with the exception of the coconut and pandanus.

From Proto-Polynesian *tau. Cognates include Tongan tau and Samoan tau.

tau

1. (intransitive) to fight; to quarrel
2. (intransitive) to compete

From Proto-Polynesian *tau. Cognates include Maori tau and Samoan tau.

tau (plural tatau)

1. (intransitive) to hit
2. (intransitive) to land
3. (intransitive) to arrive
4. (intransitive) to anchor
5. (intransitive, of fish) to settle down

From Proto-Polynesian *tau. Cognates include Tuvaluan tau and Samoan tau.

tau

1. (transitive, of months) to count

From Proto-Polynesian *tau. Cognates include Rapa tau and Samoan tau.

tau

1. The point where the keel meets the stern of the canoe.

tau

1. Fresh nest fern leaves, used to cover a traditional oven.

tau

1. Used to indicate the exclusiveness of the following noun or pronoun; just, only, merely

tau

1. Used to indicate the focus lies on the following noun; concerning, regarding

tau

1. Used to indicate that the action of the following verb is beginning; starting to; beginning to

tau

1. Only used in tau ma (“to be fed up with”)

• R. Simona, editor (1986), Tokelau Dictionary‎, Auckland: Office of Tokelau Affairs, page 342

From Proto-Polynesian *tau, from Proto-Malayo-Polynesian *taʀuŋ.

• IPA^(key): /ta.u/

tau

1. fight

• IPA^(key): /tà.ú/

tau class 9/10 (plural ditau)

1. lion

• (Vinh) IPA^(key):

• (Hà Nội) IPA^(key):
• (Huế) IPA^(key):
• (Saigon) IPA^(key):

tau

1. North Central Vietnam form of tao (“I/me”)

• tua

• (North Wales) IPA^(key): /taɨ̯/
• (South Wales) IPA^(key): /tai̞/

tau

1. (literary) third-person singular present indicative/future of tewi

From Proto-Hmong-Mien *təuk, from Old Chinese 得 (OC *tɯːɡ).^[1]

• IPA^(key): /tau̯˧/

tau

1. to get, gain, obtain
2. (used preverbally) perfective action marker

   Kuv tsis tau ua. ― I didn't do that.

3. (used postverbally) potential mood marker

   Ua tau. ― May be done.

• Heimbach, Ernest E. (1979) White Hmong — English Dictionary‎, SEAP Publications, →ISBN.

tau

1. fire